{"id":"F2009L00163","name":"AD/BO 105/26 - Tail Rotor - Balance Weights","slug":"ad-bo-105-26-tail-rotor-balance-weights","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":76599,"registerId":"commonwealth-F2009L00163-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"Eurocopter BO 105 Series Helicopters","sectionType":"division","heading":"Eurocopter BO 105 Series Helicopters","content":"### Eurocopter BO 105 Series Helicopters\n\n| AD/BO 105/26 | Tail Rotor - Balance Weights | 2/2009 |\n| ------------ | ---------------------------- | ------ |\n\n| Applicability: | Eurocopter Deutschland (ECD) GmbH Models BO 105 A, BO 105 C,BO 105 LS A-1, BO 105 D, BO 105 DS, BO 105DB, BO 105 DBS, BO 105 DB-4, BO 105 DBS-4, BO 105 DBS-5 and BO 105 S helicopters, all serial numbers.                                                                                                                                                                                                                                                                                                                       |\n| -------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Requirement:   | 1. Inspect the tail rotor balance weights and control levers in accordance with ECD BO105 Alert Service Bulletin (ASB) No. ASB BO105-30-116.2. If, during any inspection as detailed in Requirement 1 of this AD, damage is detected which exceeds the acceptable limits as specified in the ASB, replace the affected components with serviceable parts.Replacement of parts does not constitute terminating action for the repetitive inspection requirements of this AD.Note: EASA AD 2008-0206 dated 25 November 2008 refers. |\n| Compliance:    | For Requirement 1 - Within the next 2 months or 100 flight hours (FH), whichever occurs first after the effective date of this AD, and thereafter at intervals not to exceed 600 FH (+ 60 FH) or 48 months (+ 6 months), whichever occurs first.For Requirement 2 - Before further flight.                                                                                                                                                                                                                                        |\n|                | This Airworthiness Directive becomes effective on 12 February 2009.                                                                                                                                                                                                                                                                                                                                                                                                                                                               |\n| Background:    | During a periodical inspection, corrosion was detected on the tail rotor balance weights in the area of the attachment thread. This condition, if not detected and corrected, could lead to failure of the threads, possibly resulting in separation of tail rotor parts, subsequent severe tail rotor vibration and consequent loss of control of the helicopter.                                                                                                                                                                |\n\n|     | For the reasons described above, this AD requires repetitive visual inspections of the tail rotor balance weights and control levers to identify any damage and the replacement of damaged components. |\n| --- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |\n\n![](image.001.png)  \nJames Coyne  \nDelegate of the Civil Aviation Safety Authority\n\n22 December 2008","sortOrder":0},{"sectionNumber":"AD/BO 105/26","sectionType":"part","heading":"AD/BO 105/26","content":"## AD/BO 105/26","sortOrder":1},{"sectionNumber":"Tail Rotor - Balance Weights","sectionType":"part","heading":"Tail Rotor - Balance Weights","content":"## Tail Rotor - Balance Weights","sortOrder":2},{"sectionNumber":"2/2009","sectionType":"part","heading":"2/2009","content":"## 2/2009","sortOrder":3}],"analysis":{"flash_summary_failed":{"failed":true,"reason":"A positive credit balance is required for all requests, including BYOK, so fallback providers remain available. Add credits at https://vercel.com/d?to=%2F%5Bteam%5D%2F%7E%2Fai%3Fmodal%3Dtop-up to continue.","source":"analysis-cron"},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a standard, targeted Airworthiness Directive addressing a specific safety-of-flight issue (corrosion in tail rotor components). The scope remains precisely focused on the identified defect and the affected helicopter fleet. There is no evidence of scope creep or expansion beyond the original safety purpose."},"complexity_factors":["Single, clearly defined applicability (specific helicopter models by serial number)","Two straightforward requirements: inspect, and replace if damaged","Simple compliance timeline with clear intervals (flight hours OR calendar time)","Only one external reference (Eurocopter Alert Service Bulletin ASB BO105-30-116)","No nested exceptions, conditional logic, or extensive defined terms","Background and rationale clearly stated in plain language","Total length is approximately one page"],"plain_english_summary":"This AD mandates regular inspections of tail rotor balance weights and control levers on Eurocopter BO 105-series helicopters for corrosion or damage and requires replacement of parts that exceed limits before flight. It affects owners, operators and maintenance personnel of the listed BO 105 variants. The inspections start within 2 months or 100 flight hours, and must be repeated every 600 flight hours or 48 months; the aim is to prevent thread failure, rotor separation, severe vibration and potential loss of control."},"flash_summary":{"complexity_score":4,"scope_assessment":{"changed":false,"description":"Scope remains focused on repetitive visual inspections and replacement of tail rotor balance weights and control levers for the listed BO 105 variants to address thread corrosion risk (Applicability; Requirement; Background). The AD does not expand applicability beyond the named models or introduce alternative mandated modifications; it specifies inspection intervals, tolerances and that part replacement does not terminate ongoing inspections (Requirement; Compliance)."},"complexity_factors":["Technical inspection standard is delegated to ECD ASB BO105-30-116.2 rather than fully described in the AD (Requirement).","Judgement required to determine whether detected damage ‘exceeds the acceptable limits’ specified in the ASB (Requirement).","Dual compliance metrics with tolerances: initial deadline of 2 months or 100 FH (whichever first), recurring intervals not to exceed 600 FH (+60 FH) or 48 months (+6 months) (Compliance).","Replacement of parts is mandatory when limits exceeded but explicitly does not terminate the repetitive inspection obligation (Requirement).","Immediate grounding risk for defective parts: replacement required 'before further flight' if damage found (Compliance).","Wide applicability across multiple BO 105 variants and all serial numbers, increasing the affected operator population (Applicability).","Safety-critical consequence (tail rotor thread failure → possible separation and loss of control) increases enforcement and reporting scrutiny (Background).","Operational and scheduling burden for operators to fit inspections/replacements into maintenance cycles and secure serviceable parts and qualified personnel (implied by Requirement and Compliance)."],"plain_english_summary":"This airworthiness directive requires operators of listed Eurocopter BO 105 series helicopters to carry out repetitive visual inspections of tail rotor balance weights and control levers per ECD ASB BO105‑30‑116.2, and to replace any components with damage beyond the ASB's limits. It sets an initial compliance deadline (within 2 months or 100 flight hours) and recurring intervals (600 FH or 48 months), and is intended to prevent thread corrosion that could cause tail rotor part separation and loss of control."}},"importantCases":[],"_links":{"self":"/api/acts/ad-bo-105-26-tail-rotor-balance-weights","history":"/api/acts/ad-bo-105-26-tail-rotor-balance-weights/history","analysis":"/api/acts/ad-bo-105-26-tail-rotor-balance-weights/analysis","conflicts":"/api/acts/ad-bo-105-26-tail-rotor-balance-weights/conflicts","importantCases":"/api/acts/ad-bo-105-26-tail-rotor-balance-weights/important-cases","documents":"/api/acts/ad-bo-105-26-tail-rotor-balance-weights/documents"}}